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// Copyright 2017 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.devtools.build.lib.packages;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec.VisibleForSerialization;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.EvalException;
import com.google.devtools.build.lib.syntax.FunctionSignature;
import com.google.devtools.build.lib.syntax.SkylarkType;
import com.google.devtools.build.lib.util.Pair;
import javax.annotation.Nullable;
/**
* Base class for declared providers {@see Provider} defined in native code.
*
* <p>Every non-abstract derived class of {@link NativeProvider} corresponds to a single declared
* provider. This is enforced by final {@link #equals(Object)} and {@link #hashCode()}.
*
* <p>Typical implementation of a non-constructable from Skylark declared provider is as follows:
*
* <pre>
* public static final Provider PROVIDER =
* new NativeProvider("link_params") { };
* </pre>
*
* To allow construction from Skylark and custom construction logic, override {@link
* ProviderFromFunction#createInstanceFromSkylark(Object[], Environment, Location)}.
*
* @deprecated use {@link BuiltinProvider} instead.
*/
@Immutable
@Deprecated
public abstract class NativeProvider<V extends Info> extends ProviderFromFunction {
private final NativeKey key;
private final String errorMessageFormatForUnknownField;
private final Class<V> valueClass;
public Class<V> getValueClass() {
return valueClass;
}
/**
* Implement this to mark that a native provider should be exported with certain name to Skylark.
* Broken: only works for rules, not for aspects. DO NOT USE FOR NEW CODE!
*
* <p>Use native declared providers mechanism exclusively to expose providers to both native and
* Skylark code.
*/
@Deprecated
public interface WithLegacySkylarkName {
String getSkylarkName();
}
private static final FunctionSignature.WithValues<Object, SkylarkType> SIGNATURE =
FunctionSignature.WithValues.create(FunctionSignature.KWARGS);
protected NativeProvider(Class<V> clazz, String name) {
this(clazz, name, SIGNATURE);
}
@SuppressWarnings("unchecked")
protected NativeProvider(
Class<V> valueClass,
String name,
FunctionSignature.WithValues<Object, SkylarkType> signature) {
super(name, signature, Location.BUILTIN);
Class<? extends NativeProvider<?>> clazz = (Class<? extends NativeProvider<?>>) getClass();
key = new NativeKey(name, clazz);
this.valueClass = valueClass;
errorMessageFormatForUnknownField = String.format("'%s' object has no attribute '%%s'", name);
}
/**
* equals() implements singleton class semantics.
*
* <p>Every non-abstract derived class of {@link NativeProvider} corresponds to a single declared
* provider.
*/
@Override
public final boolean equals(@Nullable Object other) {
return other != null && this.getClass().equals(other.getClass());
}
/**
* hashCode() implements singleton class semantics.
*
* <p>Every non-abstract derived class of {@link NativeProvider} corresponds to a single declared
* provider.
*/
@Override
public final int hashCode() {
return getClass().hashCode();
}
@Override
public String getPrintableName() {
return getName();
}
@Override
public String getErrorMessageFormatForUnknownField() {
return errorMessageFormatForUnknownField;
}
@Override
public boolean isExported() {
return true;
}
@Override
public NativeKey getKey() {
return key;
}
@Override
protected Info createInstanceFromSkylark(Object[] args, Environment env, Location loc)
throws EvalException {
throw new EvalException(
loc, String.format("'%s' cannot be constructed from Skylark", getPrintableName()));
}
public static Pair<String, String> getSerializedRepresentationForNativeKey(NativeKey key) {
return Pair.of(key.name, key.aClass.getName());
}
@SuppressWarnings("unchecked")
public static NativeKey getNativeKeyFromSerializedRepresentation(Pair<String, String> serialized)
throws ClassNotFoundException {
Class<? extends Provider> aClass = Class.forName(serialized.second).asSubclass(Provider.class);
return new NativeKey(serialized.first, aClass);
}
/**
* A serializable representation of {@link NativeProvider}.
*
* <p>Just a wrapper around its class.
*/
@AutoCodec
@Immutable
// TODO(cparsons): Move this class, as NativeProvider is deprecated.
public static final class NativeKey extends Key {
private final String name;
private final Class<? extends Provider> aClass;
@VisibleForSerialization
NativeKey(String name, Class<? extends Provider> aClass) {
this.name = name;
this.aClass = aClass;
}
@Override
public int hashCode() {
return aClass.hashCode();
}
@Override
public boolean equals(Object obj) {
return obj instanceof NativeKey && aClass.equals(((NativeKey) obj).aClass);
}
@Override
public String toString() {
return name;
}
}
}
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